On Sat, May 19, 2001 at 11:30:40AM +1000, Damian Conway wrote:
> I obviously didn't do an adequate job the first time.
I don't know about that, but the universe of Perl 6 properties is
looking clearer to me now and I thank you for it.
> Here, the C<true> property is being set I<on the value> in $result and that
> annotated value is then being returned. We might want to do this because
> we know the value could be 0 or "" or "0", but we'd still like to be
> able to write:
>
> if ($res = gorkulator) {
> ...
> }
This seems to imply that conditionals will look at certain properties
(true/false). I hope not. I'd rather that properties be explicitly
checked:
if (($res = gorkulator).true) {
...
}
If anything, all variables should have a "value" property that evaluates
to its, well, value and only that property would be considered in
conditionals. Then these would be equivalent:
print keys (+$foo).prop;
print keys $foo.value.prop;
and perhaps that would satisfy the (+$foo).prop-is-ugly slice of
people.
> $bar is Open;
> $bar is Open("from 5pm");
> $bar{soom} is Open("from 5pm");
> "bar" is Open("from 5pm");
> 1 is Open("from 5pm");
>
> Note that in the first three of the above cases, it's the I<value in the
> variable> -- not the variable itself -- that has the C<Open> sticky-note
> attached to it.
How do we know it applies to the value and not the variable? Is it
the presence of "my" that would make the difference? What about
these:
our $food is ready; # compile-time?
temp $erature is rising; # run-time?
And if it is the "my" that makes all the difference, this will need
good documentation (and appropriate warnings):
sub CheckBar {
...
return my $bar is Open;
}
$barstat = CheckBar();
if ($barstat.Open) { ... } # Oops, $barstat.Open doesn't exist
> The answer is that methods always override property accessors of the
> same name.
...
> You may also be wondering what happens if a variable and the value it
> contains both have a property of the same name. The answer is that we
> always get back the variable's property in preference to the value's:
So, if I have a Dog $spot, here's a little table where a 1 in the M
column means $spot has a bark method that says 'woof', 1 in the V column
means $spot has a bark variable (compile-time) property that says 'arf'
and a 1 in the A column means $spot has a bark value (run-time) property
that says 'yip'.
MVA $spot.bark (+$spot).bark
000 Error Error
001 yip yip
010 arf Error
011 arf yip
100 woof woof
101 woof woof
110 woof woof
111 woof woof
yes?
-Scott
--
Jonathan Scott Duff
[EMAIL PROTECTED]
